964 resultados para Stocks -- Rate of return
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The standard approach to signal reconstruction in frequency-domain optical-coherence tomography (FDOCT) is to apply the inverse Fourier transform to the measurements. This technique offers limited resolution (due to Heisenberg's uncertainty principle). We propose a new super-resolution reconstruction method based on a parametric representation. We consider multilayer specimens, wherein each layer has a constant refractive index and show that the backscattered signal from such a specimen fits accurately in to the framework of finite-rate-of-innovation (FRI) signal model and is represented by a finite number of free parameters. We deploy the high-resolution Prony method and show that high-quality, super-resolved reconstruction is possible with fewer measurements (about one-fourth of the number required for the standard Fourier technique). To further improve robustness to noise in practical scenarios, we take advantage of an iterated singular-value decomposition algorithm (Cadzow denoiser). We present results of Monte Carlo analyses, and assess statistical efficiency of the reconstruction techniques by comparing their performance against the Cramer-Rao bound. Reconstruction results on experimental data obtained from technical as well as biological specimens show a distinct improvement in resolution and signal-to-reconstruction noise offered by the proposed method in comparison with the standard approach.
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We address the problem of parameter estimation of an ellipse from a limited number of samples. We develop a new approach for solving the ellipse fitting problem by showing that the x and y coordinate functions of an ellipse are finite-rate-of-innovation (FRI) signals. Uniform samples of x and y coordinate functions of the ellipse are modeled as a sum of weighted complex exponentials, for which we propose an efficient annihilating filter technique to estimate the ellipse parameters from the samples. The FRI framework allows for estimating the ellipse parameters reliably from partial or incomplete measurements even in the presence of noise. The efficiency and robustness of the proposed method is compared with state-of-art direct method. The experimental results show that the estimated parameters have lesser bias compared with the direct method and the estimation error is reduced by 5-10 dB relative to the direct method.
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This paper derives outer bounds for the 2-user symmetric linear deterministic interference channel (SLDIC) with limited-rate transmitter cooperation and perfect secrecy constraints at the receivers. Five outer bounds are derived, under different assumptions of providing side information to receivers and partitioning the encoded message/output depending on the relative strength of the signal and the interference. The usefulness of these outer bounds is shown by comparing the bounds with the inner bound on the achievable secrecy rate derived by the authors in a previous work. Also, the outer bounds help to establish that sharing random bits through the cooperative link can achieve the optimal rate in the very high interference regime.
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This paper derives outer bounds on the sum rate of the K-user MIMO Gaussian interference channel (GIC). Three outer bounds are derived, under different assumptions of cooperation and providing side information to receivers. The novelty in the derivation lies in the careful selection of side information, which results in the cancellation of the negative differential entropy terms containing signal components, leading to a tractable outer bound. The overall outer bound is obtained by taking the minimum of the three outer bounds. The derived bounds are simplified for the MIMO Gaussian symmetric IC to obtain outer bounds on the generalized degrees of freedom (GDOF). The relative performance of the bounds yields insight into the performance limits of multiuser MIMO GICs and the relative merits of different schemes for interference management. These insights are confirmed by establishing the optimality of the bounds in specific cases using an inner bound on the GDOF derived by the authors in a previous work. It is also shown that many of the existing results on the GDOF of the GIC can be obtained as special cases of the bounds, e. g., by setting K = 2 or the number of antennas at each user to 1.
Resumo:
Standard approaches for ellipse fitting are based on the minimization of algebraic or geometric distance between the given data and a template ellipse. When the data are noisy and come from a partial ellipse, the state-of-the-art methods tend to produce biased ellipses. We rely on the sampling structure of the underlying signal and show that the x- and y-coordinate functions of an ellipse are finite-rate-of-innovation (FRI) signals, and that their parameters are estimable from partial data. We consider both uniform and nonuniform sampling scenarios in the presence of noise and show that the data can be modeled as a sum of random amplitude-modulated complex exponentials. A low-pass filter is used to suppress noise and approximate the data as a sum of weighted complex exponentials. The annihilating filter used in FRI approaches is applied to estimate the sampling interval in the closed form. We perform experiments on simulated and real data, and assess both objective and subjective performances in comparison with the state-of-the-art ellipse fitting methods. The proposed method produces ellipses with lesser bias. Furthermore, the mean-squared error is lesser by about 2 to 10 dB. We show the applications of ellipse fitting in iris images starting from partial edge contours, and to free-hand ellipses drawn on a touch-screen tablet.
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On the basis of the well-known shear-lag analysis of fibre/matrix interface stresses and the assumption of identical axial strains in the fibre and matrix, a new model for predicting the energy release rate of interfacial fracture of the fibre pull-out test model is attempted. The expressions for stresses in the fibre, matrix and interface are derived. The formula for interfacial debonding energy release rate is given. Numerical calculations are conducted and the results obtained are compared with those of the existing models.
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在四辊冷轧试验机和Gleeble-1500试验机上进行了热轧微碳钢板的冷轧和退火试验。用D/max-RC衍射仪测量了试样的,/”层织构,并用Roe软件进行了ODF分析。研究表明,所研究的热轧微碳深冲板压下率约为75%,退火升温速度为20-40℃/h时,试样为{111}织构特征;压下率较大(80%)时,退火织构为较弱的{111}组分。无论{111}织构还是非{111}织构都是在形核阶段开始形成,在晶粒长大优先长大,受到定向形核和选择生长双重机制的作用。
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Y-Ba-Cu-O (YBCO) single grains have the potential to generate large trapped magnetic fields for a variety of engineering applications, and research on the processing and properties of this material has attracted world-wide interest. In particular, the introduction of flux pinning centres to the large grain microstructure to improve its current density, Jc, and hence trapped field, has been investigated extensively over the past decade. Y 2Ba4CuMOx [Y-2411(M)], where M = Nb, Ta, Mo, W, Ru, Zr, Bi and Ag, has been reported to form particularly effective flux pinning centres in YBCO due primarily to its ability to exist as nano-size inclusions in the superconducting phase matrix. However, the addition of the Y-2411(M) phase to the precursor composition complicates the melt-processing of single grains. We report an investigation of the growth rate of single YBCO grains containing Y-2411(Bi) phase inclusions and Y2O3. The superconducting properties of these large single grains have been measured specifically to investigate the effect of Y2O3 on broadening the growth window of these materials. © 2010 IOP Publishing Ltd.
Resumo:
An investigation of fiber/matrix interfacial fracture energy is presented in this paper. Several existing theoretical expressions for the fracture energy of interfacial debonding are reviewed. For the single-fiber/matrix debonding and pull-out experimental model, a study is carried out on the effect of interfacial residual compressive stress and friction on interface cracking energy release rate.
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A new statistical formulation and a relevant experimental approach to determine the growth rate of microcracks were proposed. The method consists of experimental measurements and a statistical analysis' on the basis of the conservation law of number density of microcracks in phase space. As a practical example of the method, the growth rate of microcracks appearing in an aluminium alloy subjected to planar impact loading was determined to be ca. 10 mu m/mu s under a tensile stress of 1470 MPa and load duration between 0.26 mu s and 0.80 mu s.
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Giant cutgrass ( Zizaniopsis miliacea (Michx.) Doell. & Asch.), a tall emergent grass native to the southeastern United States, was studied in Lake Seminole where it formed large expanding stands, and Lake Alice where it was confined to a stable narrow fringe.
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CONTENTS: I. U.S.-Japan Cooperation Open Ocean Aquaculture – A Venue for Cooperative Research Between the United States and Japan.............................................................................. 1 C. Helsley II. Growth, Nutrition and Genetic Diversity Daily Ration of Hatchery-Reared Japanese Flounder Paralichthys olivaceus as an Indicator of Release Place, Time and Fry Quality. In situ Direct Estimation and Possibility of New Methods by Stable Isotope............................ 7 O. Tominaga, T. Seikai, T. Tsusaki, Y. Hondo, N. Murakami, K. Nogami, Y. Tanaka and M. Tanaka Nucleic Acids and Protein Content as a Measure to Evaluate the Nutritional Condition of Japanese Flounder Paralichthys olivaceus Larvae and Juveniles........................................................................................................ 25 W. Gwak Genetic Diversity Within and Between Hatchery Strains of Flounder Paralichthys olivaceus Assessed by Means of Microsatellite and Mitochondrial DNA Sequencing Analysis...................................................................... 43 M. Sekino, M. Hara and N. Taniguchi Tracking Released Japanese Flounder Paralichthys olivaceus by Mitochondrial DNA Sequencing................................................................................ 51 T. Fujii Preliminary Aspects of Genetic Management for Pacific Threadfin Polydactylus sexfilis Stock Enhancement Research in Hawaii........................................ 55 M. Tringali, D. Ziemann and K. Stuck Enhancement of Pacific Threadfin Polydactylus sexfilis in Hawaii: Interactions Between Aquaculture and Fisheries............................................................. 75 D. Ziemann Aquaculture and Genetic Structure in the Japanese Eel Anguilla japonica..................... 87 M. Katoh and M. Kobayashi Comparative Diets and Growth of Two Scombrid Species, Chub Mackerel Scomber japonicus and Japanese Spanish Mackerel Scomberomorus niphonius, in the Central Seto Inland Sea, Japan.................................. 93 J. Shoji, M. Tanaka and Tsutomu Maehara iii Evaluating Stock Enhancement Strategies: A Multi-disciplinary Approach................... 105 T. M. Bert, R.H. McMichael, Jr., R.P. Cody, A. B. Forstchen, W. G. Halstead, K. M. Leber, J. O’Hop, C. L. Neidig, J. M. Ransier, M. D. Tringali, B. L. Winner and F. S. Kennedy III. Physiological and Ecological Applications Predation on Juvenile Chum Salmon Oncorhynchus keta by Fishes and Birds in Rivers and Coastal Oceanic Waters of Japan................................... 127 K. Nagasawa and H. Kawamura Interaction Between Cleaner and Host: The Black Porgy Cleaning Behavior of Juvenile Sharpnose Tigerfish Rhyncopelates Oxyrhynchus in the Seto Inland Sea, Western Japan............................................................................. 139 T. Shigeta, H. Usuki and K. Gushima IV. Case Studies Alaska Salmon Enhancement: A Successful Program for Hatchery and Wild Stocks............................................................................................... 149 W. Heard NMFS Involvement with Stock Enhancement as a Management Tool........................... 171 T. McIlwain Stock Enhancement Research with Anadromous and Marine Fishes in South Carolina...................................................................................... 175 T. I. J. Smith, W. E. Jenkins, M. R. Denson and M. R. Collins Comparison of Some Developmental, Nutritional, Behavioral and Health Factors Relevant to Stocking of Striped Mullet, (Mugilidae), Sheepshead (Sparidae), Common Snook (Centropomidae) and Nassau Groupers (Serranidae)........................... 191 J. W. Tucker Jr. and S. B. Kennedy Participants in the Thirtieth U.S.-Japan Meeting on Aquaculture................. Inside Back Cover iv (PDF has 204 pages.)
Resumo:
ENGLISH: The present paper describes a new method for estimating the shedding rate of tags. The method utilizes not only data on tagging and recovery of fish marked with two tags but also data from those marked with one. One important advantage of the new technique is that the estimates of the shedding rates are free from distortion caused by variations in fishing intensity during the total recovery period. The idea of this method appears to be implicit in a short note by Gulland (1963). This technique has been applied to the data obtained by the Inter-American Tropical Tuna Commission in a tagging cruise off the west coast of southern Baja California, during June 1963, at which time both single and double-tagged yellowfin tuna were released. Details of the tagging procedure and equipment have been described by Fink (1965b). The results presented in the present paper are for yellowfin tuna tagged with dart tags. Estimates of shedding should be made separately for each species investigated and also for each type of tag used, since these rates may be variable and often unexpectedly high (Springer and McErlean 1961, Chadwick 1963). SPANISH: El presente estudio describe un nuevo método para estimar las tasas del desprendimiento de marcas. El método emplea no solamente los datos sobre la marcación y recobro de peces marcados con dos marcas, pero también datos de los peces marcados con una marca. Una ventaja importante de la nueva técnica, es que las estimaciones de las tasas de desprendimiento son libres de alteración, causada por las variaciones en la intensidad de pesca durante el período total de recobro. La idea de este método parece ser implícita en un breve apunte por Gulland (1963). Esta técnica se ha aplicado a los datos obtenidos por la Comisión Interamericana del Atún Tropical, en un crucero de marcación efectuado frente a la costa occidental al sur de Baja California, en junio de 1963, tiempo en el cual fueron liberados atunes aleta amarilla marcados tanto con una como con dos marcas. Los detalles del procedimiento de la marcación y del equipo usado han sido descritos por Fink (1965b). Los resultados presentados en este estudio, pertenecen al atún aleta amarilla marcado con marcas de dardo. Las estimaciones del desprendimiento deben efectuarse separadamente para cada especie que ha sido investigada y también para cada tipo de marca usado, ya que estas tasas pueden ser vaiables, y a menudo inesperadamente altas (Springer y McErlean 1961, Chadwick 1963). (PDF contains 20 pages.)